Anti-terror police near Paris were on Saturday still interrogating killer Mohamed Merah's older brother Abdelkader, transferred from detention in the southwestern city of Toulouse on Saturday along with his girlfriend.
Mohamed Merah, 23, was labelled a "monster" by French President Nicolas Sarkozy after he killed three Jewish children, a trainee rabbi and three soldiers in three separate gun attacks this month in or near Toulouse.
He was killed on Thursday in a hail of bullets as he tried to shoot his way out of a Toulouse apartment after a 32-hour siege.
Abdelkader Merah, 29, taken into custody on Wednesday, admitted being present when the scooter his brother used in the killings was stolen, but said he knew nothing of Mohamed's intentions.
He added he was "proud" of his brother, whose attacks led to the suspension of the presidential election campaign and provoked revulsion in France and beyond.
French law requires that he be charged or released early Sunday after four days in detention.
Police and prosecutors have described Abdelkader as a more radical Islamist than his brother. The elder brother has long been known to police for his "fundamentalist religious convictions", a police source said.
Police said they were investigating whether the elder brother had provided financial or logistical support to the shooter -something Abdelkader denied.
Mohamed Merah told police during the siege that he had bought his weapons using money from burglaries and hold-ups, France's national intelligence coordinator Ange Mancini told BFM-TV Saturday.
Abdelkader Merah's partner has also denied any involvement in the case, saying she was surprised and shocked to have been taken into custody, her lawyer Guy Debuisson told BFM-TV.
On Wednesday, Paris prosecutor Francois Molins said it appeared Abdelkader may have been involved in a network that took jihadists to Iraq in 2007.
Mohamed's mother Zoulhika Aziri, released without charge on Friday, was "wracked with guilt and remorse" over her son's actions, her lawyer Jean-Yves Gougnaud said. Fearing reprisals, she would not return home, he added.
In the killer's Toulouse neighbourhood, police deterred about 30 people from holding a small rally, banned by the authorities, in memory of Merah and to support his mother.
Large gatherings are being planned nationwide for Sunday, including an inter-religious march in Toulouse.
On Sarkozy held an emergency meeting on Saturday with Prime Minister Francois Fillon and cabinet ministers to discuss security issues amid criticism of the way police handled the affair.
The president later defended the RAID special police unit involved in the siege, saying: "I will not allow anyone to question the honour of RAID and the forces who brought an end to this monstrous individual's actions."
Speculation is rife over Merah's motives and whether he had any accomplices. He had claimed to be an Al-Qaeda member killing to avenge Palestinian children and punish France for sending troops to Afghanistan.
Interior Minister Claude Gueant told Saturday's Le Figaro that Merah was a "terrorist acting alone" and hit back at critics of the intelligence services and the police operation.
But Christian Prouteau, who founded the GIGN, another elite unit drawn from the military police, said Merah could have been captured alive if teargas had been used. Israeli security experts have also criticised the police operation.
During the siege, Merah told police that he travelled to Pakistan in 2011, said the head of France's DCRI domestic intelligence agency, Bernard Squarcini.
But he said he had been trained by a single individual, not at a training centre where spies could have reported his presence.
French agents had investigated Merah after his trip to Afghanistan, but had found no danger signs, Squarcini added.
"No ideological activism, no visiting mosques."
The body of Imad Ben Ziaten, the 31-year-old French paratrooper who was the first of Merat's victims, was flown back for burial in his native Morocco late Saturday, accompanied by France's minister for army veterans Marc Laffineur.